feat(ui): Help overlay with Info/Donate tabs, fixed dimensions

Help button now shows a fixed-size two-tab overlay:

Info tab: app name + version, one-line description, thin separator,
  © 2026 Davide Grilli — MIT License, Built with .NET 10 · Avalonia 12 · NBitcoin.

Donate tab: dev address (plm1qdq3…) read-only display, free amount
  input, prepare-preview row, confirm-and-broadcast button.

Overlay dimensions are stable across tabs and between desktop/mobile:
- TabControl Height=320 (fixed, never resizes on tab switch)
- HorizontalAlignment=Stretch + MaxWidth=440 on the card (always fills
  available width; previously Center caused the card to shrink to content
  width, which differed between Info and Donate)
- Each tab content wrapped in ScrollViewer for safe overflow handling

New MainWindowViewModel.Donate.cs: PrepareDonate / ConfirmDonate /
ResetDonate (called on overlay close). Six-language Loc keys added for
all donate strings.

src/App/Localization/Loc.cs

@@ -60,6 +60,19 @@ public sealed class Loc
             "Portefeuille SPV pour la cryptomonnaie Palladium (PLM).",
             "Carteira SPV para a criptomoeda Palladium (PLM).",
             "SPV-Wallet für die Kryptowährung Palladium (PLM)."],
+        ["help.tab.info"]         = ["Info",                                                               "Info",                         "Info",                                 "Info",                                     "Info",                                     "Info"],
+        ["help.tab.donate"]       = ["Dona",                                                               "Donate",                       "Donar",                                "Faire un don",                             "Doar",                                     "Spenden"],
+        ["donate.desc"]           = [
+            "Se questo wallet ti è utile, considera una piccola donazione allo sviluppatore.",
+            "If you find this wallet useful, consider a small donation to the developer.",
+            "Si esta wallet te resulta útil, considera una pequeña donación al desarrollador.",
+            "Si ce portefeuille vous est utile, envisagez un petit don au développeur.",
+            "Se esta carteira é útil para você, considere uma pequena doação ao desenvolvedor.",
+            "Wenn Ihnen dieses Wallet nützlich ist, erwägen Sie eine kleine Spende an den Entwickler."],
+        ["donate.dev.address"]    = ["Indirizzo sviluppatore",                                             "Developer address",            "Dirección del desarrollador",          "Adresse du développeur",                   "Endereço do desenvolvedor",                "Entwickleradresse"],
+        ["donate.amount"]         = ["Importo donazione",                                                  "Donation amount",              "Monto de donación",                    "Montant du don",                           "Valor da doação",                          "Spendenbetrag"],
+        ["donate.prepare"]        = ["Prepara donazione",                                                  "Prepare donation",             "Preparar donación",                    "Préparer le don",                          "Preparar doação",                          "Spende vorbereiten"],
+        ["donate.confirm"]        = ["Conferma e invia",                                                   "Confirm and send",             "Confirmar y enviar",                   "Confirmer et envoyer",                     "Confirmar e enviar",                       "Bestätigen und senden"],
         ["settings.unit.short"]   = ["Unità",                                                             "Unit",                         "Unidad",                               "Unité",                                    "Unidade",                                  "Einheit"],
 
         // Wizard

src/App/Styles/Controls.axaml

@@ -117,6 +117,11 @@
     <Style Selector="TabItem:selected /template/ ContentPresenter#PART_ContentPresenter">
         <Setter Property="TextElement.Foreground" Value="{DynamicResource PrimaryBrush}"/>
     </Style>
+    <!-- Push tab header content up so the 2px selection indicator (drawn at Panel bottom)
+         does not overlap the text label. -->
+    <Style Selector="TabItem /template/ ContentPresenter#PART_ContentPresenter">
+        <Setter Property="Margin" Value="0,0,0,4"/>
+    </Style>
 
     <!-- ===== Reusable classes ===== -->
     <!-- Card: elevated surface with a subtle border and soft corners -->

src/App/ViewModels/MainWindowViewModel.Donate.cs

@@ -0,0 +1,96 @@
+using System;
+using System.Threading.Tasks;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using NBitcoin;
+using PalladiumWallet.Core.Chain;
+using PalladiumWallet.Core.Net;
+using PalladiumWallet.Core.Wallet;
+
+namespace PalladiumWallet.App.ViewModels;
+
+public partial class MainWindowViewModel
+{
+    public const string DevAddress = "plm1qdq3gu2zvg9lyr8gxd6yln4wavc5tlp8prmvfay";
+
+    [ObservableProperty]
+    private string donateAmount = "";
+
+    [ObservableProperty]
+    private string donatePreview = "";
+
+    [ObservableProperty]
+    private bool hasPendingDonate;
+
+    private BuiltTransaction? _pendingDonate;
+
+    [RelayCommand]
+    private async Task PrepareDonate()
+    {
+        _pendingDonate = null;
+        HasPendingDonate = false;
+
+        if (_account is null || _doc?.Cache is null || _lastTransactions is null)
+        {
+            DonatePreview = "Sincronizza prima di inviare.";
+            return;
+        }
+        try
+        {
+            var destination = BitcoinAddress.Create(DevAddress, PalladiumNetworks.For(Net));
+            if (!CoinAmount.TryParseIn(DonateAmount.Trim(), _config.Unit, out var amount) || amount <= 0)
+            {
+                DonatePreview = "Importo non valido.";
+                return;
+            }
+            if (!decimal.TryParse(SendFeeRate, System.Globalization.NumberStyles.Any,
+                    System.Globalization.CultureInfo.InvariantCulture, out var feeRate) || feeRate <= 0)
+                feeRate = 1m;
+
+            _pendingDonate = new TransactionFactory(_account).Build(
+                _doc.Cache.Utxos, _lastTransactions, destination, amount, feeRate,
+                _doc.Cache.NextChangeIndex, sendAll: false);
+
+            DonatePreview = $"txid {_pendingDonate.Txid[..16]}… · " +
+                $"fee {Fmt(_pendingDonate.Fee.Satoshi)} " +
+                $"({_pendingDonate.Transaction.GetVirtualSize()} vB)" +
+                (_pendingDonate.Signed ? "" : " · watch-only");
+            HasPendingDonate = _pendingDonate.Signed;
+        }
+        catch (Exception ex)
+        {
+            _pendingDonate = null;
+            HasPendingDonate = false;
+            DonatePreview = $"Errore: {ex.Message}";
+        }
+        await Task.CompletedTask;
+    }
+
+    [RelayCommand]
+    private async Task ConfirmDonate()
+    {
+        if (_pendingDonate is null || _client is null)
+            return;
+        try
+        {
+            var txid = await _client.BroadcastAsync(_pendingDonate.ToHex());
+            DonatePreview = $"Grazie! txid: {txid}";
+            DonateAmount = "";
+            _pendingDonate = null;
+            HasPendingDonate = false;
+            await ConnectAndSync();
+        }
+        catch (Exception ex)
+        {
+            DonatePreview = $"Errore broadcast: {ex.Message}";
+        }
+    }
+
+    private void ResetDonate()
+    {
+        DonateAmount = "";
+        DonatePreview = "";
+        HasPendingDonate = false;
+        _pendingDonate = null;
+    }
+}

src/App/ViewModels/MainWindowViewModel.Settings.cs

@@ -70,5 +70,5 @@ public partial class MainWindowViewModel
     private void OpenHelp() => IsHelpOpen = true;
 
     [RelayCommand]
-    private void CloseHelp() => IsHelpOpen = false;
+    private void CloseHelp() { IsHelpOpen = false; ResetDonate(); }
 }

src/App/ViewModels/MainWindowViewModel.cs

@@ -96,6 +96,11 @@ public partial class MainWindowViewModel : ViewModelBase
 
     public bool IsMobile => !IsDesktop;
 
+    // Tab bar sizing: compact on mobile so all 5 tabs fit in one row.
+    public double TabIconSize  => IsMobile ? 20 : 24;
+    public double TabFontSize  => IsMobile ? 10 : 13;
+    public double TabSpacing   => IsMobile ? 4  : 4;
+
     public string UnitLabel => _config.Unit;
     public AppConfig CurrentConfig => _config;
 

src/App/Views/MainView.axaml

@@ -324,7 +324,7 @@
                         <Setter Property="Background" Value="{DynamicResource SurfaceBrush}"/>
                         <Setter Property="ItemsPanel">
                             <ItemsPanelTemplate>
-                                <UniformGrid Rows="1"/>
+                                <UniformGrid Rows="1" Columns="5"/>
                             </ItemsPanelTemplate>
                         </Setter>
                     </Style>
@@ -332,22 +332,25 @@
                         <Setter Property="HorizontalAlignment" Value="Stretch"/>
                         <Setter Property="HorizontalContentAlignment" Value="Center"/>
                         <Setter Property="VerticalContentAlignment" Value="Center"/>
-                        <Setter Property="Padding" Value="8,14"/>
-                        <Setter Property="MinWidth" Value="80"/>
+                        <Setter Property="Padding" Value="8,12"/>
                     </Style>
                 </TabControl.Styles>
 
                 <!-- 1. History -->
                 <TabItem>
                     <TabItem.Header>
-                        <StackPanel Spacing="4" HorizontalAlignment="Center">
-                            <Viewbox Width="24" Height="24" HorizontalAlignment="Center">
+                        <StackPanel Spacing="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabSpacing}"
+                                        HorizontalAlignment="Center">
+                                <Viewbox Width="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabIconSize}"
+                                         Height="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabIconSize}"
+                                         HorizontalAlignment="Center">
                                     <Canvas Width="24" Height="24">
                                         <Path Fill="{Binding $parent[TabItem].Foreground}"
                                               Data="M7,5H21V7H7V5M7,13V11H21V13H7M4,4.5A1.5,1.5 0 0,1 5.5,6A1.5,1.5 0 0,1 4,7.5A1.5,1.5 0 0,1 2.5,6A1.5,1.5 0 0,1 4,4.5M4,10.5A1.5,1.5 0 0,1 5.5,12A1.5,1.5 0 0,1 4,13.5A1.5,1.5 0 0,1 2.5,12A1.5,1.5 0 0,1 4,10.5M7,19V17H21V19H7M4,16.5A1.5,1.5 0 0,1 5.5,18A1.5,1.5 0 0,1 4,19.5A1.5,1.5 0 0,1 2.5,18A1.5,1.5 0 0,1 4,16.5Z"/>
                                     </Canvas>
                                 </Viewbox>
-                            <TextBlock Text="{Binding Loc[tab.history]}" FontSize="13"
+                                <TextBlock Text="{Binding Loc[tab.history]}"
+                                           FontSize="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabFontSize}"
                                            HorizontalAlignment="Center"/>
                             </StackPanel>
                     </TabItem.Header>
@@ -393,14 +396,18 @@
                 <!-- 2. Send -->
                 <TabItem>
                     <TabItem.Header>
-                        <StackPanel Spacing="4" HorizontalAlignment="Center">
-                            <Viewbox Width="24" Height="24" HorizontalAlignment="Center">
+                        <StackPanel Spacing="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabSpacing}"
+                                        HorizontalAlignment="Center">
+                                <Viewbox Width="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabIconSize}"
+                                         Height="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabIconSize}"
+                                         HorizontalAlignment="Center">
                                     <Canvas Width="24" Height="24">
                                         <Path Fill="{Binding $parent[TabItem].Foreground}"
                                               Data="M2,21L23,12L2,3V10L17,12L2,14V21Z"/>
                                     </Canvas>
                                 </Viewbox>
-                            <TextBlock Text="{Binding Loc[tab.send]}" FontSize="13"
+                                <TextBlock Text="{Binding Loc[tab.send]}"
+                                           FontSize="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabFontSize}"
                                            HorizontalAlignment="Center"/>
                             </StackPanel>
                     </TabItem.Header>
@@ -496,34 +503,41 @@
                         </Grid>
 
                         <!-- ── MOBILE: vertical stack ── -->
-                        <StackPanel IsVisible="{Binding IsMobile}" Spacing="14">
-                            <Border Classes="card" Padding="20,16">
-                                <StackPanel Spacing="12">
+                        <StackPanel IsVisible="{Binding IsMobile}" Spacing="12">
+
+                            <!-- Recipient card with labelled inputs -->
+                            <Border Classes="card" Padding="20,18">
+                                <StackPanel Spacing="14">
                                     <TextBlock Text="{Binding Loc[send.sect.recipient]}" Classes="section"/>
-                                    <Grid ColumnDefinitions="Auto,*">
-                                        <TextBlock Grid.Column="0" Text="{Binding Loc[send.from.contact]}"
-                                                   VerticalAlignment="Center" Margin="0,0,10,0"
-                                                   Foreground="{DynamicResource TextSecondaryBrush}" FontSize="13"/>
-                                        <ComboBox Grid.Column="1" HorizontalAlignment="Stretch"
+                                    <!-- Contact picker -->
+                                    <StackPanel Spacing="4">
+                                        <TextBlock Text="{Binding Loc[send.from.contact]}" Classes="label"/>
+                                        <ComboBox HorizontalAlignment="Stretch"
                                                   ItemsSource="{Binding Contacts}"
                                                   SelectedItem="{Binding SendToContact}"
-                                                  PlaceholderText="{Binding Loc[send.contact.hint]}">
+                                                  PlaceholderText="{Binding Loc[send.contact.hint]}"
+                                                  MinHeight="48">
                                             <ComboBox.ItemTemplate>
                                                 <DataTemplate x:DataType="vm:ContactEntry">
-                                                    <TextBlock Text="{Binding Name}"/>
+                                                    <TextBlock Text="{Binding Name}" FontSize="15"/>
                                                 </DataTemplate>
                                             </ComboBox.ItemTemplate>
                                         </ComboBox>
-                                    </Grid>
+                                    </StackPanel>
+                                    <!-- Address + QR scan button -->
+                                    <StackPanel Spacing="4">
+                                        <TextBlock Text="{Binding Loc[send.to]}" Classes="label"/>
                                         <Grid ColumnDefinitions="*,Auto">
                                             <TextBox Grid.Column="0"
                                                      PlaceholderText="{Binding Loc[send.to]}"
                                                      Text="{Binding SendTo}"
-                                                 FontFamily="monospace"/>
-                                        <Button Grid.Column="1" Margin="8,0,0,0" Padding="10,6"
+                                                     FontFamily="monospace" FontSize="15"
+                                                     MinHeight="48"/>
+                                            <Button Grid.Column="1" Margin="8,0,0,0"
+                                                    Width="52" Height="48"
                                                     Command="{Binding ScanQrCommand}"
                                                     ToolTip.Tip="{Binding Loc[send.scan]}">
-                                            <Viewbox Width="20" Height="20">
+                                                <Viewbox Width="22" Height="22">
                                                     <Canvas Width="24" Height="24">
                                                         <Path Fill="{DynamicResource SystemBaseHighColor}"
                                                               Data="M20,5H16.83L15,3H9L7.17,5H4A2,2 0 0,0 2,7V19A2,2 0 0,0 4,21H20A2,2 0 0,0 22,19V7A2,2 0 0,0 20,5M20,19H4V7H8.05L9.88,5H14.12L15.95,7H20V19M12,8A5,5 0 0,0 7,13A5,5 0 0,0 12,18A5,5 0 0,0 17,13A5,5 0 0,0 12,8M12,16A3,3 0 0,1 9,13A3,3 0 0,1 12,10A3,3 0 0,1 15,13A3,3 0 0,1 12,16Z"/>
@@ -532,26 +546,44 @@
                                             </Button>
                                         </Grid>
                                     </StackPanel>
+                                </StackPanel>
                             </Border>
-                            <Border Classes="card" Padding="20,16">
-                                <StackPanel Spacing="12">
+
+                            <!-- Amount & fee card with labelled inputs -->
+                            <Border Classes="card" Padding="20,18">
+                                <StackPanel Spacing="14">
                                     <TextBlock Text="{Binding Loc[send.sect.amount]}" Classes="section"/>
-                                    <Grid ColumnDefinitions="*,Auto,Auto">
-                                        <TextBox Grid.Column="0" PlaceholderText="0.00000000"
-                                                 Text="{Binding SendAmount}" IsEnabled="{Binding !SendAll}"
-                                                 FontFamily="monospace"/>
+                                    <!-- Amount field -->
+                                    <StackPanel Spacing="4">
+                                        <TextBlock Text="{Binding Loc[send.amount]}" Classes="label"/>
+                                        <Grid ColumnDefinitions="*,Auto">
+                                            <TextBox Grid.Column="0"
+                                                     PlaceholderText="0.00000000"
+                                                     Text="{Binding SendAmount}"
+                                                     IsEnabled="{Binding !SendAll}"
+                                                     FontFamily="monospace" FontSize="16"
+                                                     MinHeight="48"/>
                                             <TextBlock Grid.Column="1" Text="{Binding UnitLabel}"
-                                                   VerticalAlignment="Center" Margin="8,0,0,0"
+                                                       VerticalAlignment="Center" Margin="12,0,0,0"
+                                                       FontWeight="Medium"
                                                        Foreground="{DynamicResource TextSecondaryBrush}"/>
-                                        <CheckBox Grid.Column="2" Content="{Binding Loc[send.all]}"
-                                                  IsChecked="{Binding SendAll}" Margin="10,0,0,0"/>
                                         </Grid>
-                                    <StackPanel Orientation="Horizontal" Spacing="8">
-                                        <TextBlock Text="{Binding Loc[send.feerate]}" VerticalAlignment="Center" Classes="label"/>
-                                        <TextBox Text="{Binding SendFeeRate}" MinWidth="80" FontFamily="monospace"/>
+                                    </StackPanel>
+                                    <!-- Send-all toggle -->
+                                    <CheckBox Content="{Binding Loc[send.all]}"
+                                              IsChecked="{Binding SendAll}"
+                                              MinHeight="44" FontSize="14"/>
+                                    <!-- Fee rate field -->
+                                    <StackPanel Spacing="4">
+                                        <TextBlock Text="{Binding Loc[send.feerate]}" Classes="label"/>
+                                        <TextBox Text="{Binding SendFeeRate}"
+                                                 FontFamily="monospace" FontSize="15"
+                                                 MinHeight="48" HorizontalAlignment="Stretch"/>
                                     </StackPanel>
                                 </StackPanel>
                             </Border>
+
+                            <!-- Summary card -->
                             <Border Classes="card" Padding="20,16"
                                     IsVisible="{Binding SendPreview, Converter={x:Static StringConverters.IsNotNullOrEmpty}}">
                                 <StackPanel Spacing="8">
@@ -561,15 +593,19 @@
                                                          Foreground="{DynamicResource TextSecondaryBrush}"/>
                                 </StackPanel>
                             </Border>
-                            <Grid ColumnDefinitions="*,*" ColumnSpacing="12">
-                                <Button Grid.Column="0" Content="{Binding Loc[send.prepare]}"
-                                        Command="{Binding PrepareSendCommand}"
-                                        HorizontalAlignment="Stretch" HorizontalContentAlignment="Center"/>
-                                <Button Grid.Column="1" Content="{Binding Loc[send.confirm]}" Classes="accent"
+
+                            <!-- Action buttons: primary (Confirm) prominent, secondary below -->
+                            <Button Content="{Binding Loc[send.confirm]}" Classes="accent"
                                     Command="{Binding ConfirmSendCommand}"
                                     IsEnabled="{Binding HasPendingSend}"
+                                    MinHeight="52"
+                                    HorizontalAlignment="Stretch" HorizontalContentAlignment="Center"
+                                    FontSize="15"/>
+                            <Button Content="{Binding Loc[send.prepare]}"
+                                    Command="{Binding PrepareSendCommand}"
+                                    MinHeight="48"
                                     HorizontalAlignment="Stretch" HorizontalContentAlignment="Center"/>
-                            </Grid>
+
                         </StackPanel>
 
                     </Panel>
@@ -579,14 +615,18 @@
                 <!-- 3. Receive -->
                 <TabItem>
                     <TabItem.Header>
-                        <StackPanel Spacing="4" HorizontalAlignment="Center">
-                            <Viewbox Width="24" Height="24" HorizontalAlignment="Center">
+                        <StackPanel Spacing="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabSpacing}"
+                                        HorizontalAlignment="Center">
+                                <Viewbox Width="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabIconSize}"
+                                         Height="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabIconSize}"
+                                         HorizontalAlignment="Center">
                                     <Canvas Width="24" Height="24">
                                         <Path Fill="{Binding $parent[TabItem].Foreground}"
                                               Data="M2,12H4V17H20V12H22V17A2,2 0 0,1 20,19H4A2,2 0 0,1 2,17V12M12,15L17,10L15.59,8.58L13,11.17V2H11V11.17L8.41,8.59L7,10L12,15Z"/>
                                     </Canvas>
                                 </Viewbox>
-                            <TextBlock Text="{Binding Loc[tab.receive]}" FontSize="13"
+                                <TextBlock Text="{Binding Loc[tab.receive]}"
+                                           FontSize="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabFontSize}"
                                            HorizontalAlignment="Center"/>
                             </StackPanel>
                     </TabItem.Header>
@@ -635,39 +675,49 @@
                         </Grid>
 
                         <!-- ── MOBILE: vertical stack ── -->
-                        <StackPanel IsVisible="{Binding IsMobile}" Spacing="14">
-                            <Border Classes="card" Padding="24,20"
+                        <StackPanel IsVisible="{Binding IsMobile}" Spacing="12">
+
+                            <!-- QR card: full-width, centered with generous padding -->
+                            <Border Classes="card" Padding="24,22"
                                     IsVisible="{Binding ReceiveQr, Converter={x:Static ObjectConverters.IsNotNull}}">
-                                <StackPanel Spacing="18" HorizontalAlignment="Center">
+                                <StackPanel Spacing="16" HorizontalAlignment="Center">
                                     <TextBlock Text="{Binding Loc[receive.next]}" Classes="label"
-                                               HorizontalAlignment="Center"/>
-                                    <Border Background="White" Padding="14" CornerRadius="10"
+                                               HorizontalAlignment="Center" FontSize="13"/>
+                                    <Border Background="White" Padding="16" CornerRadius="12"
                                             HorizontalAlignment="Center">
-                                        <Image Source="{Binding ReceiveQr}" Width="200" Height="200"
+                                        <Image Source="{Binding ReceiveQr}" Width="220" Height="220"
                                                RenderOptions.BitmapInterpolationMode="None"/>
                                     </Border>
                                 </StackPanel>
                             </Border>
-                            <Border Classes="card" Padding="20,18">
-                                <StackPanel Spacing="12">
+
+                            <!-- Address card: label + monospace box + big Copy button -->
+                            <Border Classes="card" Padding="20,20">
+                                <StackPanel Spacing="14">
                                     <TextBlock Text="{Binding Loc[receive.your.address]}" Classes="section"/>
                                     <Border Background="{DynamicResource SurfaceAltBrush}"
-                                            CornerRadius="8" Padding="14,10">
+                                            CornerRadius="8" Padding="16,12">
                                         <SelectableTextBlock Text="{Binding ReceiveAddress}"
-                                                             FontFamily="monospace" FontSize="13"
+                                                             FontFamily="monospace" FontSize="14"
                                                              TextWrapping="Wrap"
                                                              TextAlignment="Center"
-                                                             HorizontalAlignment="Center"/>
+                                                             HorizontalAlignment="Center"
+                                                             LineHeight="22"/>
                                     </Border>
                                     <Button Content="{Binding Loc[receive.copy]}" Classes="accent"
                                             Click="OnCopyReceiveAddressClick"
+                                            MinHeight="52"
                                             HorizontalAlignment="Stretch"
-                                            HorizontalContentAlignment="Center"/>
+                                            HorizontalContentAlignment="Center"
+                                            FontSize="15"/>
                                 </StackPanel>
                             </Border>
+
+                            <!-- Hint -->
                             <TextBlock Text="{Binding Loc[receive.hint]}"
                                        Foreground="{DynamicResource TextSecondaryBrush}" FontSize="12"
                                        TextWrapping="Wrap" TextAlignment="Center" Margin="4,0"/>
+
                         </StackPanel>
 
                     </Panel>
@@ -677,14 +727,18 @@
                 <!-- 4. Addresses -->
                 <TabItem>
                     <TabItem.Header>
-                        <StackPanel Spacing="4" HorizontalAlignment="Center">
-                            <Viewbox Width="24" Height="24" HorizontalAlignment="Center">
+                        <StackPanel Spacing="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabSpacing}"
+                                        HorizontalAlignment="Center">
+                                <Viewbox Width="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabIconSize}"
+                                         Height="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabIconSize}"
+                                         HorizontalAlignment="Center">
                                     <Canvas Width="24" Height="24">
                                         <Path Fill="{Binding $parent[TabItem].Foreground}"
                                               Data="M21,18V19A2,2 0 0,1 19,21H5C3.89,21 3,20.1 3,19V5A2,2 0 0,1 5,3H19A2,2 0 0,1 21,5V6H12C10.89,6 10,6.9 10,8V16A2,2 0 0,0 12,18H21M12,16H22V8H12V16M16,13.5A1.5,1.5 0 0,1 14.5,12A1.5,1.5 0 0,1 16,10.5A1.5,1.5 0 0,1 17.5,12A1.5,1.5 0 0,1 16,13.5Z"/>
                                     </Canvas>
                                 </Viewbox>
-                            <TextBlock Text="{Binding Loc[tab.addresses]}" FontSize="13"
+                                <TextBlock Text="{Binding Loc[tab.addresses]}"
+                                           FontSize="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabFontSize}"
                                            HorizontalAlignment="Center"/>
                             </StackPanel>
                     </TabItem.Header>
@@ -739,14 +793,18 @@
                 <!-- 5. Contacts -->
                 <TabItem>
                     <TabItem.Header>
-                        <StackPanel Spacing="4" HorizontalAlignment="Center">
-                            <Viewbox Width="24" Height="24" HorizontalAlignment="Center">
+                        <StackPanel Spacing="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabSpacing}"
+                                        HorizontalAlignment="Center">
+                                <Viewbox Width="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabIconSize}"
+                                         Height="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabIconSize}"
+                                         HorizontalAlignment="Center">
                                 <Canvas Width="24" Height="24">
                                     <Path Fill="{Binding $parent[TabItem].Foreground}"
                                           Data="M16,13C15.71,13 15.38,13 15.03,13.05C16.19,13.89 17,15 17,16.5V19H23V16.5C23,14.17 18.33,13 16,13M8,13C5.67,13 1,14.17 1,16.5V19H15V16.5C15,14.17 10.33,13 8,13M8,11A3,3 0 0,0 11,8A3,3 0 0,0 8,5A3,3 0 0,0 5,8A3,3 0 0,0 8,11M16,11A3,3 0 0,0 19,8A3,3 0 0,0 16,5C15.71,5 15.42,5.03 15.14,5.09C15.68,5.95 16,6.94 16,8C16,9.06 15.68,10.05 15.14,10.91C15.42,10.97 15.71,11 16,11Z"/>
                                 </Canvas>
                             </Viewbox>
-                            <TextBlock Text="{Binding Loc[tab.contacts]}" FontSize="13"
+                            <TextBlock Text="{Binding Loc[tab.contacts]}"
+                                       FontSize="{Binding $parent[TabControl].((vm:MainWindowViewModel)DataContext).TabFontSize}"
                                        HorizontalAlignment="Center"/>
                         </StackPanel>
                     </TabItem.Header>
@@ -1315,17 +1373,88 @@
             <Border Background="{DynamicResource OverlayCardBrush}"
                     BorderBrush="{DynamicResource BorderSubtleBrush}" BorderThickness="1" CornerRadius="8"
                     MaxWidth="440" Margin="16"
-                    HorizontalAlignment="Center" VerticalAlignment="Center">
+                    HorizontalAlignment="Stretch" VerticalAlignment="Center">
                 <StackPanel Margin="24" Spacing="16">
                     <TextBlock Text="{Binding Loc[help.title]}"
                                FontSize="18" FontWeight="Bold"/>
 
+                    <!-- Fixed height so the overlay never resizes when switching tabs. -->
+                    <TabControl Height="320">
+                        <!-- Tab: Info -->
+                        <TabItem Header="{Binding Loc[help.tab.info]}">
+                            <ScrollViewer VerticalScrollBarVisibility="Auto">
+                                <StackPanel Spacing="12" Margin="0,12,0,0">
                                     <StackPanel Spacing="4">
                                         <TextBlock Text="Palladium Wallet" FontSize="16" FontWeight="Bold"/>
-                        <TextBlock Text="{Binding WindowTitle}" FontSize="12" Foreground="{DynamicResource TextSecondaryBrush}"/>
+                                        <TextBlock Text="{Binding WindowTitle}" FontSize="12"
+                                                   Foreground="{DynamicResource TextSecondaryBrush}"/>
+                                    </StackPanel>
+                                    <TextBlock Text="{Binding Loc[help.info]}" TextWrapping="Wrap"/>
+                                    <Border BorderBrush="{DynamicResource BorderSubtleBrush}"
+                                            BorderThickness="0,1,0,0" Margin="0,4,0,0"/>
+                                    <StackPanel Spacing="4">
+                                        <TextBlock Text="© 2026 Davide Grilli — MIT License"
+                                                   FontSize="12"
+                                                   Foreground="{DynamicResource TextSecondaryBrush}"/>
+                                        <TextBlock Text="Built with .NET 10 · Avalonia 12 · NBitcoin"
+                                                   FontSize="11"
+                                                   Foreground="{DynamicResource TextSecondaryBrush}"/>
+                                    </StackPanel>
+                                </StackPanel>
+                            </ScrollViewer>
+                        </TabItem>
+
+                        <!-- Tab: Donate -->
+                        <TabItem Header="{Binding Loc[help.tab.donate]}">
+                            <ScrollViewer VerticalScrollBarVisibility="Auto">
+                                <StackPanel Spacing="12" Margin="0,12,0,0">
+                                    <TextBlock Text="{Binding Loc[donate.desc]}" TextWrapping="Wrap"
+                                               Foreground="{DynamicResource TextSecondaryBrush}"/>
+
+                                    <!-- Dev address (read-only) -->
+                                    <StackPanel Spacing="4">
+                                        <TextBlock Text="{Binding Loc[donate.dev.address]}" FontSize="11"
+                                                   Foreground="{DynamicResource TextSecondaryBrush}"/>
+                                        <SelectableTextBlock Text="{x:Static vm:MainWindowViewModel.DevAddress}"
+                                                             FontFamily="monospace" FontSize="11"
+                                                             TextWrapping="Wrap"/>
                                     </StackPanel>
 
-                    <TextBlock Text="{Binding Loc[help.info]}" TextWrapping="Wrap"/>
+                                    <!-- Amount input -->
+                                    <StackPanel Spacing="4">
+                                        <TextBlock Text="{Binding Loc[donate.amount]}" FontSize="11"
+                                                   Foreground="{DynamicResource TextSecondaryBrush}"/>
+                                        <Grid ColumnDefinitions="*,Auto">
+                                            <TextBox Grid.Column="0"
+                                                     Text="{Binding DonateAmount}"
+                                                     PlaceholderText="{Binding UnitLabel}"/>
+                                            <TextBlock Grid.Column="1" Text="{Binding UnitLabel}"
+                                                       VerticalAlignment="Center" Margin="8,0,0,0"
+                                                       Foreground="{DynamicResource TextSecondaryBrush}"/>
+                                        </Grid>
+                                    </StackPanel>
+
+                                    <!-- Preview -->
+                                    <SelectableTextBlock Text="{Binding DonatePreview}"
+                                                         IsVisible="{Binding DonatePreview,
+                                                             Converter={x:Static StringConverters.IsNotNullOrEmpty}}"
+                                                         FontFamily="monospace" FontSize="11"
+                                                         TextWrapping="Wrap"
+                                                         Foreground="{DynamicResource TextSecondaryBrush}"/>
+
+                                    <!-- Buttons -->
+                                    <StackPanel Orientation="Horizontal" Spacing="8" HorizontalAlignment="Right">
+                                        <Button Content="{Binding Loc[donate.confirm]}"
+                                                Classes="accent"
+                                                IsEnabled="{Binding HasPendingDonate}"
+                                                Command="{Binding ConfirmDonateCommand}"/>
+                                        <Button Content="{Binding Loc[donate.prepare]}"
+                                                Command="{Binding PrepareDonateCommand}"/>
+                                    </StackPanel>
+                                </StackPanel>
+                            </ScrollViewer>
+                        </TabItem>
+                    </TabControl>
 
                     <Button Content="{Binding Loc[addr.close]}"
                             HorizontalAlignment="Right"